Aerosol particles collected at urban locations contain a significant portion of automobile exhaust emissions, especially lead and zinc.
The most important emitted gases, carbon monoxide (CO), hydrocarbons (HC), and the nitrogen oxides (NOx) play an important role in the formation of photochemical smog in urban areas.
Nitrate formation through heterogenous reactions on dust particles may provide a removal mechanism for the nitrogen oxides in the atmosphere.
As a consequence dust can reduce ozone formation rates by up to 25%. At 47 sites within the city of Graz, Austria dust particles were collected.
Two hundred particles with a diameter of about 1mum were analyzed with a Laser Microphobe Mass Analyzer (LAMMA) for each sampling point : one half for laser generated cations and the other half for anions.
The frequencies of occurence of elements in 100 particles were used as a measure for the air quality.
Isolines (lines of equal element frequencies) were employed to outline polluted regions and identify the sources of dust particles.
A summation method was used to monitor nitrogen oxides.
Particles nitrate correlateds well with lead frequencies in aerosols as well as with NOx levels.
This indicates that the NOx emitted by traffic exhaust is at least partially deposited on particulate matter.
Mots-clés Pascal : Hydrocarbure, Azote oxyde, Autriche, Europe, Zone urbaine, Aérosol, Smog, Gaz échappement, Carbone monoxyde, Réaction photochimique, Graz
Mots-clés Pascal anglais : Hydrocarbon, Nitrogen oxide, Austria, Europe, Urban area, Aerosols, Smog, Exhaust gas, Carbon monoxide, Photochemical reaction
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 98-0500787
Code Inist : 002B30A02A. Création : 19/02/1999.